Typed lengths, stations and unit text

/** Metres per unit for linear units found in files (LandXML linearUnit names). */
export const METRES_PER = { USSurveyFoot: 1200 / 3937, foot: 0.3048, ft: 0.3048, meter: 1, m: 1, metre: 1, millimeter: 0.001, centimeter: 0.01, kilometer: 1000 };

/** One length as CivilCraft reads it → its value in project units (null when it is not one). */
function oneLength(x, unit) {
  let s = String(x).trim().toLowerCase().replace(/\s+/g, ' ');
  if (isNum(s)) return Number(s);
  const toUnit = (metres) => (unit === 'm' ? metres : metres / M_PER_IN / 12);   // feet project: inches to feet as 12 to 1
  const m = s.match(/^(\d+(?:\.\d*)?|\.\d+) ?(mm|cm|m)$/);
  if (m) return toUnit(Number(m[1]) * (m[2] === 'mm' ? 0.001 : m[2] === 'cm' ? 0.01 : 1));
  // a number with a fraction: 4 7/16, 4-7/16, 7/16 (in the unit it stands in)
  const frac = (q) => { const f = q.trim().match(/^(?:(\d+)[ -])?(\d+)\/(\d+)$/); if (f) return f[3] === '0' ? null : (Number(f[1] || 0) + Number(f[2]) / Number(f[3])); return isNum(q.trim()) ? Number(q) : null; };
  const bare = frac(s);
  if (bare !== null) return bare;
  // feet and inches: 12'6", 12' 6 1/2", 12'-6", 6", 3 ft 6 in, 3ft, 6 in
  s = s.replace(/\b(feet|foot|ft)\b\.?/g, "'").replace(/\b(inches|inch|in)\b\.?/g, '"').replace(/''/g, '"');
  const fi = s.match(/^(?:([\d./ -]+?) ?')?(?: ?-? ?([\d./ -]+?) ?")?$/);
  if (!fi || (!fi[1] && !fi[2])) return tableLength(x, unit);
  const ft = fi[1] ? frac(fi[1]) : 0, inch = fi[2] ? frac(fi[2]) : 0;
  if (ft === null || inch === null) return null;
  const feet = ft + inch / 12;
  return unit === 'm' ? feet * 12 * M_PER_IN : feet;
}

/** "12+34.56" (ft) or "1+234.567" (m). Negative stations keep their sign in front: "-0+50.00". */
export function formatStation(sta, unit = 'ft', dec) {
  if (!Number.isFinite(sta)) return '';
  const u = unitOf(unit), d = dec ?? u.staDec;
  const neg = sta < 0;
  const r = Number(Math.abs(sta).toFixed(d));
  const big = Math.floor(r / u.staLen + 1e-9);
  let rest = r - big * u.staLen;
  if (rest < 0) rest = 0;
  const w = String(u.staLen).length - 1;   // digits before the point: 2 for ft, 3 for m
  const restStr = rest.toFixed(d).padStart(w + (d ? d + 1 : 0), '0');
  return (neg ? '-' : '') + big + '+' + restStr;
}

/** Parses "12+34.56", "1234.56", "-0+50" → number (in the project unit), or null. */
export function parseStation(s, unit = 'ft') {
  const t = String(s ?? '').trim().replace(/\s+/g, '');
  if (!t) return null;
  const m = t.match(/^([+-]?)(\d+)\+(\d+(?:\.\d*)?)$/);
  if (m) {
    const v = Number(m[2]) * unitOf(unit).staLen + Number(m[3]);
    return m[1] === '-' ? -v : v;
  }
  return isNum(t) ? Number(t) : null;
}

/**
 * A volume in the unit's report unit (cu yd for feet, cu m for metres), or in the volume unit starred in Settings ›
 * General › Units (0.7 UNITS: acre-feet, litres …); the same for areas (acres, hectares …).
 */
export function volumeText(v, unit = 'ft', d = 1) {
  const s = starred('volume', unit, { ft: 'yd3', m: 'm3' });
  if (s) return grouped(fromBase(v * (M_PER_UNIT[unit] || M_PER_UNIT.ft) ** 3, s.id), s.dec) + ' ' + s.mark;
  const u = unitOf(unit); return grouped(v / u.volPer, d) + ' ' + u.vol;
}

export function areaText(a, unit = 'ft', d = 0) {
  const s = starred('area', unit, { ft: 'ft2', m: 'm2' });
  if (s) return grouped(fromBase(a * (M_PER_UNIT[unit] || M_PER_UNIT.ft) ** 2, s.id), s.dec) + ' ' + s.mark;
  return grouped(a, d) + ' ' + unitOf(unit).area;
}

/** Bearing text for a direction angle (radians, math convention: 0 = east, CCW) → N 45°12'30" E. */
export function bearing(a) {
  let az = (90 - a * 180 / Math.PI) % 360;   // azimuth from north, clockwise
  if (az < 0) az += 360;
  let q, ang;
  if (az <= 90) { q = ['N', 'E']; ang = az; } else if (az <= 180) { q = ['S', 'E']; ang = 180 - az; } else if (az <= 270) { q = ['S', 'W']; ang = az - 180; } else { q = ['N', 'W']; ang = 360 - az; }
  return q[0] + ' ' + dms(ang) + ' ' + q[1];
}

export function dms(deg) {
  let s = Math.round(Math.abs(deg) * 3600);
  const d = Math.floor(s / 3600); s -= d * 3600;
  const m = Math.floor(s / 60); s -= m * 60;
  return d + '°' + String(m).padStart(2, '0') + "'" + String(s).padStart(2, '0') + '"';
}